We are interested in using Saccharomyces cerevisiae as our model system to study chromosome replication in eukaryotes. By means of conventional genetics and current techniques developed in molecular cloning, we hope to dissect the complex chromosomes into simple replication units so as to: (1) study the structure, complexity and organization of individual replication initiation sites (replicators), and (2) examine the signals that activate replication at these sites. By gathering the information from these studies, we hope to learn something about the replication of chromosomes as a whole and the control mechanism which initiates their replication.